Tetrasila-adamantane compounds

ABSTRACT

The sulfate salts of tetrasila-adamantane compounds in which at least one silicon atom is substituted with a nitrogen-containing radical, such as   ARE USEFUL AS EMULSIFIERS.

United States Patent [191 Frye et al.

[ TETRASlLA-ADAMANTANE COMPOUNDS [75] Inventors: Cecil L. Frye, Midland; Jerome M.

Klosowski, Monitor Twp., Bay County, both of Mich.

[731 Assignee: Dow Corning Corporation, Midland,

Mich.

[52] I U.S. CL... 260/297 F; 260/297 F; 260/4482 B; 260/448.2 D [51] Int. Cl C07d 103/02 [58] Field of Search... 260/297 F, 448.2 B, 448.2 D

[56] References Cited UNITED STATES PATENTS 3,631,195 12/1971 Frye et a]. 260/448.2 E

[ June 17, 1975 12/1971 Klosowski 260/448.2 D 12/1971 Klosowski et a1. 260/448.2 E

Primary Examiner--G. Thomas Todd Attorney, Agent, or FirmNorman E. Lewis 7] f ABSTRACT The sulfate salts of tetrasila-adamantane compounds in which at least one silicon atom is substituted with a nitrogen-containing radical, such as are useful as emulsifiers.

I 24 Claims, No Drawings TETRASILA-ADAMANTANE COMPOUNDS This is a division of application Se'r. No. 230,937, filed Mar. 1, 1972; now US. Pat. No. 3,776,915.

This invention relates to novel tetrasila-adamantanes which have at least one nitrogen-containing substituent. In one aspect, the invention relates to new emulsifying agents.

Tetrasila-adamantane compounds -can be represented by the structural formula This cage structure, whose four bridgehead silicon atoms are tetrahedrally arranged, forms a tetravalent nucleus which can be conveniently represented by the symbol Ad. The methyl-substituted tetrasilaadamantane, (CH Ad, has been produced by the pyrolysis of tetramethylsilane at about 650C. see Fritz et al, Carbosilanes, Advances in Inorganic and Radiochemistry, Volume 7, page 349, Academic Press (1965). The chlorinated compound, AdCl was obtained in very low yield from the high temperature (500C.) reaction of tetrachlorosilane and trimethylchlorosilane in the presence of aluminum chloride as reported in JACS, 83, 3345 (1961). These compounds are stable to hydrolysis and the utility of such compounds is limited; the only reported utility being that of mosquito repellency for the chloro-substituted tetrasila-adamantane compounds. Hydrogen-functional tetrasila adamantanes have been synthesized by reduction of the chlorinated compounds see Sommer Stereo-Chemistry, Mechanism and Silicon, McGraw-Hill (1965) at page 156.

Accordingly, it is an object of the present invention to provide novel, useful tetrasila-adamantane compounds.

In accordance with the invention, there are provided l,3,5,7-tetrasila-adamantane compounds of the general formula R 51 cu on, on,

| R.-s1 ca. .Si-R,

on, 1 on,

in which R is a nitrogen-containing substituent selected from the group consisting of the NR radical wherein each R is independently selected from the group consisting of the hydrogen atom and monovalent hydrocarbon radicals containing from one to 18 inclusive carbon atoms, no more than one R radical being a hydrogen atom; the

radical wherein Q is a divalent hydrocarbonradical containing from two to nine inclusive carbon atoms; the O-QN(R") radical wherein Q is a divalent hydrocarbon radical containing from one to 20 carbons and each R" is selected from the group consisting of R radicals and oxygen-substituted monovalent hydrocarbon radicals of no more than eight carbon atoms containing oxygen in the form of hydroxyl groups; the

-0(CH=m I 1 a k radical in which R is independently selected from the group consisting of the hydrogen atom and alkyl radicals containing from one to four inclusive carbon atoms and m is an integer having a value of 2 or 3; the CH NR"" radical in which each R"" is selected from the group consisting of the hydrogen atom and monovalent hydrocarbon radicals free of aliphatic unsaturation and containing no more than eight carbon atoms and the ONR"" radical in which R' is as defined above; and each R substituent is independently selected from the group consisting of the methyl radical and R radicals.

The requisite nitrogen-containing substituent (R) can be of the formula NR where R is as defined. The monovalent hydrocarbon radicals include alkygroups, such as methyl, ethyl, propyl, octyl, and dodecyl; alkenyl groups, such as ally] and h ex'enyl; cycloaliphatic groups, such as cyclopentyl, cyclohexyl and cyclohexenyl; alkaryl or aralkyl groups such as benzyl and ,B-phenylethyl; and aryl groups such as phenyl, tolyl and naphthyl. The preferred R radicals are alkyl radicals containing from one to four carbon atoms.

Also within the scope of R are substituents wherein Q is a divalent hydrocarbon radical such as CH Cl-l a --CHzCH= H=--, H( Jmimcnnr' ((1H,); (CH3); E l-l C ll,

and the like.

When R is a -OQN(R") substituent, Q can be any divalent hydrocarbon radical such as Cl-l 2)z, 2)2, z)6,

and the like. The preferred radicals are CH C- H and CH CH CH In thissubstituent, R" can be a hydrogen atom, a monovalent hydrocarbon radical such as exemplified by'R or a hydroxyl substituted hydrocarbon radical of no more than eight carbon atoms. 1 Suitable oxygen substituted hydrocarbon radicals include CH CH OH, CH Cl-l(OH)Cl-l Cl-l Cl-l(Cl-l )CH(Ol-l)CH CH C(CH )(Ol-l)CH CH- CH CH CH(OH)CH and the like.

The R substituents also include radicals of the forwhere R is independently selected from the group consisting of the hydrogen atom and alkyl radicals containing from one to four inclusive carbon atoms, such as methyl, isopropyl and butyl radicals.

When the nitrogen-containing R substituent is of the formula CH-- NR" the nitrogen atom can be substituted with hydrogen atoms or monovalent hydrocarbon radicals, such as alkyl groups, for example, methyl, ethyl, butyl and octyl radicals; cycloaliphatic groups, 3 for example, cyclopentyl and cyclohexyl radicals; and aryl-containing groups, for example, benzyl, ,B-phenylethyl, B-phenylpropyl, phenyl, tolyl and xylyl radicals. Thus, compounds of the invention include 3)3 6 5)a a)a 5 11)2, 3)3 2 5) 3)3 4 S-l( 6 5): 3)a 11 2s)2 3)3 G 4 3)2s a):i ia a-z)2,

I ea? l (cu: 1 (0H,),Adn (0H,),Adl:

(CH AdON(C H (Cl-l Ad[ONI-l(C H and the like.

Except for those having CH- NR" functionality, the tetrasila-adamantanes of the invention are prepared by the reaction of (CH ),,AdX with RLi compounds in which X is a chlorine or bromine atom and' y is an integer having a value of from 0 to 3. The halosubstituted tetrasila-adamantane precursors are most easily obtained by the aluminum halide rearrangement of silmethylene compounds, such as [(CH SiCl-l The rearrangement reaction yields a product mixture AdX with appreciable amounts of the monohalo product being obtained at catalyst (AlCl or AlBr levels of from 20 to percent by weight based on the weight of silmethylene precursor. The reaction temperatures are relatively low, with temperatures of about C. giving good yields in from 1 to 4 hours. The

product mixture can be separated by means of fractional crystallization from pentane or by fractional sublimation if desired. A mixture of (CH Ad and (CH ),,AdX compounds can be used in preparing the nitrogen-containing compounds of the invention since (CH Ad is not reactive in the presently described synthesis.

The RLi reactants are readily prepared by reacting reagents, such as methyllithium or butyllithium with the corresponding amines, imines, piperidine and piperidine derivatives, amino alcohols, pyridyl alcohols or hydroxylamines. Exemplary of such nitrogencontaining precursors to the RLi reactants are ethylphenylamine, allylphenylamine, cyclohexylphenylamine, aniline, methylamine, diethylamine, di2- naphthylamine, dipentylamine, dioctadecylamine, di-2- tolyamine, ethyleneimine, trimethyleneimine, alphamethylheptamethyleneimine, 2-allyl-piperidine, 4- methyl-piperidine, 3-butyl-piperidine, 2,2,6,6-tetramethyl-piperidine, 2-propenyl-piperidine, piperolidine, ,8-(2-pyridyl)-ethanol, gamma-(4- pyridyl)propanol, ,B-(4-methylpryidyl-2)ethanol, ,B-( 6-methylpyridyl-2 )-ethanol, ,8-( 3-ethylpyridyl-4 ethanol, ethanolamine, 2-hydroxyethyl-4-tolylamine, dimethylethanolamine, bis(2-hydroxyethyl)butylamine, 2,2-dihydroxy-butylethylamine, 2,2-dihydroxy- 2,2'-dimethyldipentylamine, 2,2',2"- dipropylethylamine, triethanolamine, trispropanolamine, ethylhydroxylamine, diethylhydroxylamine, l-(hydroxyamino)propane, phenylhydroxylamine and the like.

The reaction of (CH ),,AdX with RLi can be carried out at from 20 to 100C. and generally is complete in less than 24 hours at these temperatures. The reaction can be conducted in a solvent, such as ether or hexane. The reaction mixture can be extracted with hydrochloric acid, to obtain the hydrochloric acid salt of the described nitrogen-functional tetrasilaadamantanes. These salts are stable in the dilute acid and the adamantane compounds are easily regenerated by the addition of a base.

The adamantanes containing -CH NR" functionality can be prepared by the reaction of (Cl-l ),,AdH with allylamines. The hydrogenfunctional tetrasila-adamantane precursors can be obtained from the reduction of the corresponding chlorosubstituted adamantane in the presence of lithium aluminum hydride. Suitable allylamine reactants include allylphenylamine, allylcyclohexylamine, allyltolyamine and allylphenylmethylamine. The Adl-l addition to CH =CHCH N= is conveniently carried out in a solvent, such as hexane, at reflux temperature. The addition reaction is catalyzed by a platinum compound, such as a platinum halide catalyst.

The salts of the tetrasila-adamantanes of the invention are emulsifying agents and can be utilized to form stable oil-water or water-oil emulsions. Only small amounts of the salts are used in forming stable emulsions and the optimum amount necessary for a particular emulsion can be easily determined by standard techniques.

The salts are readily formed by reaction of the adamantane compounds with dilute acids, such as hydrochloric acid, sulfuric acid, substituted sulfonic acids, hydroiodide, hydrobromide, phosphoric acid, acetic acid and trichloroacetic acid. Quaternary ammonium salts can be obtained by alkylation with agents such as methyliodide, benzyl chloride, dimethylsulfate and methyl phosphate. Thus, the invention includes the ani onic forms of the defined tetrasila-adamantanes, for example, chloride, bromide, iodide, sulfate, sulfonate, phosphate, acetate, trichloroacetate, methylsulfate and the like. Such salts can be depicted as (CH;,) AdR- y.ZY wherein Y is an anion and Z is a hydrogen atom or a hydrocarbon radical derived from the alkylating agent, such as a methyl or benzyl group. The following examples are illustrative, and not to be construed as limiting of the invention which is set forth in the claims.

EXAMPLE 1 Dimethylsilmethylene cyclic trimer 130 grams, 0.61 mole) was added to AlBr (22.5 grams, 0.085 mole) in a l-litter, three-neck round bottom flask connected to a gas bag through a cold trap. Upon applying heat, the temperature rose to approximately 100C, then gradually decreased as the tetramethylsilane was formed. The condenser was allowed to warm and the tetramethylsilane was driven over into the cold trap. After approximately 2 hours, 85 percent of the theoretical amount of tetramethylsilane had been collected and the g.l.c. analysis indicated that no starting material remained. The reaction mixture was then diluted with benzene and acetone was added to quench the catalyst. Washing with water removed most of the catalyst.

The organic layer was washed further with dilute hydrochloric acid rinsed with water and dried over sodium sulfate. The reaction mixture was distilled and the most volatile portion, (CH Ad was sublimed to the head of a spinning band column. The remaining material was a mixture of (CH Ad, (CH AdBr and (CH AdBr Samples of each were isolated and characterized by mass spectroscopy, infrared and n.m.r.

Dimethylsilmethylene cyclic trimer was reacted in the presence of 27 weight percent AlC1 following the above-described procedure to give (CH AdCl in 18 percent yield.

EXAMPLE 2 Butyllithium (6.25 milliliter of 1.6 molar solution in hexane) was slowly added to n-C H NH (1.98 grams) to obtain n-C H NHLi. A mixture of (CH ),,AdC1 which contained approximately 1.8 grams of (CH AdCl was reacted with the lithium salt by stirring at room temperature for 24 hours. The reaction mixture was then extracted with a large excess of 5 percent hydrochloric acid to form the salt, (CH AdNl-l(n-C l-l ).HCl. After separation and addition of fresh pentane, addition of sodium hydroxide to the aqueous phase gave (CH AdNH(n-C H which was isolated in 40 percent yield.

By substituting t -C.,H NH for the n-C H NH in the above reaction, (Cl-l AdNH(t-C H was obtained.

EXAMPLE 3 Butyllithium (9.8 milliliters of 1.6 molar solution in hexane) was added to piperidine 1.0 milliliter) to form I ""1 (CHA -111.1

The nearly pure product was then extracted into pentane after adding excess sodium hydroxide to the aqueous phase. Evaporation of the pentane gave in 51 percent yield.

EXAMPLE 4 Butyllithium (19 milliliters of 1.6 molar solution in hexane) was reacted with (CH NCH CH OH (2.7 grams) to form the desired lithiumalkoxide. A mixture of (CH ),,AdCl containing 0.01 mole of (CH AdCl was added. After 1 hour at reflux temperature, approximately percent of the (Cl-l AdCl had reacted. Five additional hours at reflux and removal of about onehalf the solvent resulted in percent consumption of the (CH AdCl. After diluting the organic phase with pentane, washing with water and separating the phases, the organic phase was washed with dilute hydrochloric acid to extract the product in the form of the salt,

EXAMPLE 5 Methyllithium was reacted with diethylamine to give (C H NLi, which in turn was reacted with a mixture of (CH Ad and (CH AdBr.-The reaction product was extracted and purified by the previously described method to yield (CH AdN(C H EXAMPLE 6 Butyllithium was reacted with methylamine to give Cl-l NHLi, which in turn was reacted with (CH AdCl. The reaction mixture was extracted with hydrochloric acid to obtain (CH AdNl-l(Cl-l l-lCl as a crystalline product.

EXAMPLE 7 Sulfate I and hydrochloride salts of tetrasilaadamantanes were utilized as emulsifying agents for mixtures of mineral oil and water. In forming the emulsions, 2 grams of mineral oil were mixed with 2 grams of aqueous hydrochloric or sulfuric acid (10 percent solutions) and 0.1 grams of the tetrasila-adamantane compound. The mixture was placed in a small vial and shaken vigorously. Forpurposes of comparison, amines which were used as precursors to the functional adamantanes were also tested (in the same manner) for effectiveness as emulsifiers. The composition of the compound tested, acid used and stability of the emulsion are given below:

. 8 sti tuted adamantanes as emulsifiers only sufficient acid to protonate one or two of the nitrogen atoms is added. The fully protonated. salts of such trior tetrasubstituted compounds are relatively ineffective as emulsifying agents. EXAMPLE 9 Lithium aluminum hydride (0.5 gram) was added to 100 ml. of ether and refluxed in a three-necked flask equipped with a condenser for about 1 hour. A mixture of (CH ).,Ad, (CH AdCl and (CH AdBr s.5 x 10" mol of AdX compound) in ether was added to the lithium aluminum hydride solution. The mixture was refluxed for 24 hours, after which ether and acetone were added. After refluxing for an additional hour and cooling .to about room temperature, the reaction mixture was poured into dilute hydrochloric acid. After No. Composition Tested Acid Present Emulsion Characteristics l (CH;,) NCH CH OH None no emulsion formed 2 (CH NCH-,CH OH H 50 no emulsion formed 3 (CH,-,) NCH CH OH HCl no emulsion formed 4 (CH NCH CH- O-Ad(CH;.);, H 50 good water-oil emulsion-mo change or separation after 10 days 5 (CH;,) NCH CH O Ad(CH HCI good'water-oil emulsion-mo change or separation after l days (no 'change or separation .was observed in a comparable emulsion after a period of 6 months) 6 l(CH NCH CH O] Ad(CH;,) HCI gogd water-oil emulsion-Fstable after 10 ays 7 (C.,H,,)NH HCI no emulsion 8 (C H,,)NH-Ad(CH HCl good water-oil emulsion-mo separation v after 12 days 9 (C H NCl i Ch Q-Ad(CH HCI good water-oil emulsion--stable after 10 days l0 (CH;,) NCH CH OH H 50 no emulsion formed* 7 l l (CH NCH Ch O Ad(CH;,) H- ,SO good water-oil emulsion formed-stable for 10 da 5* l2 (C H NH HCI no emuliion formed l3 (C H N-Ad(CH HCI water-oil emulsion stable for a few minutes l4 (C,;H,,-,NH HCl no emulsion formed 7 l5 (C H )NH-Ad(CH HCI water-oil emulsion stable for a few minutes (lrimcthylsilyl-tcrminutcd dimethylpolysiloxunc oil having a viscosity of I000 ccntistokcs at C. was suhstitutcd for the mineral oil componentof the test mixture.

These data demonstrate the effectiveness of the sulfate and hydrochloride salts of the tetrasilaadamantanes as emulsifying agents."

EXAMPLE 8 7 any (mum), and Ad(Nc.iI,)'.

was isolated by distillation of the solvent. A small amount (-6 X 10 mole) of this product mixture was added to a mixture containing 2 milliliters of mineral separation of the phases, the aqueous phase was again extracted with ether. The solvent was allowed to evaporate to obtain a product containing (CH AdH.

When allylmethylphenylamine is reacted with the (CH Adl-l product in hexane containing chloroplatinic acid at reflux for about 18 hours, there is obtained (CH AdCH CH CH NCH (C H .as the product.

' EXAMPLE 10 A small amount (0.5 grams) of (CH AdOCl-l CH N(Cl-l was mixed with 3 grams oil, 2 milliliters of water and 0.06 grams (-6 X 10') of concentrated hydrochloric acid. Shaking of the mixture gave a'water-oil emulsion in the oilphase which was stable for several hours. I

It is to be noted that when using trior tetrasubof methyliodide. The quaternization reaction was complete within 30 minutes. a The quaternary salt, (CH AdOCl-l Cl-l N(Cl-l l was filtered, washed with hexane and dried to obtain a quantitative yield of the product. The quaternary salt structure was confirmed by n.m.r. analysis. The salt (05 grams) was mixed with 2 ml. of water and 2 ml. of mineral oil to form an emulsion which remained stable after one week. For purposes of comparison, dimethylethanolamine and the methyliodide salt thereof were tested as emulsifiers in the above described oil and water mixture. Neither acted as emulsifiers.

Another quaternary salt, (CH AdN(C H Cl-l I, was obtained by mixing (CH AdN(C H with a tenfold excess of methyliodide and adding hexane to the That which is claimed is:

1. A tetrasila-adamantane of the formula on; fill in which R is a nitrogen-containing substituent selected from the group consisting of the OQ'N(R") radical wherein Q is a divalent hydrocarbon radical containing from one to carbon atoms, said divalent radical being selected from the group consisting of alkylene, alkarylene and arylene radicals; and each R" is selected from the group consisting of the hydrogen atom, monovalent hydrocarbon radicals, said hydrocarbon radical being selected from the group consisting of alkyl of one to l8 carbon atoms, alkenyl of three to l8 carbon atoms, cycloaliphatic of five to six carbon atoms, alkaryl of six to nine carbon atoms, aralkyl of six to nine carbon atoms, phenyl and naphthyl, and monohydroxy-substituted alkyl radicals of no more then eight carbon atoms the radical in which R' is independently selected from the group consisting of the hydrogen atom and alkyl radicals containing from one to four inclusive carbon atoms and m is an integer having a value of 2 or 3; the CH- NR" radical in which each R" is selected from the group consisting of the hydrogen atom and mono- LII valent hydrocarbon radicals free of aliphatic unsaturation and containing no more than eight carbon atoms and the ONR" radical in which R" is as defined above; and R is independently selected from the group consisting of the methyl radical and R radicals.

2. A compound in accordance with claim 1 wherein at least one R substituent is a methyl radical.

3. A compound in accordance with claim 2 wherein all of the R substituents are methyl radicals.

4. A compound in accordance with claim 1 wherein the R substituent is a -OQ'N(R) radical.

5. A compound in accordance with claim 4 wherein at least one R substituent is a methyl radical.

6. A compound in accordance with claim 5 wherein all of the R substituents are methyl radicals.

7. A compound in accordance with claim 5 wherein Q is an alkylene radical.

8. A compound in accordance with claim 7 wherein I R is a methyl radical.

9. A compound in accordance with claim 8 wherein R is O(CH N(Cl-l 10. A compound in accordance with claim 7 wherein at least one R radical is a hydroxyl-substituted alkyl radical.

11. A compound in accordance with claim 1 wherein R is a radical.

12. A compound in accordance with claim 1 wherein R is a Cl-l NR"" radical.

13. A compound in accordance with claim 12 wherein R is a CH NCH (C H radical.

14. A compound in accordance with claim 13 wherein all of the R substituents are methyl radicals.

15. A compound in accordance with claim 1 wherein R is a ONR"" radical.

16. The amine hydrochloride salt of the compound of claim 1.

17. The sulfate salt of the compound of claim 1.

18. The amine hydroiodide salt of the compound of claim 1.

19. The amine hydrobromide salt of the compound of claim 1.

20. The sulfonate salt of the compound of claim 1.

21. The phosphate salt of the compound of claim 1.

22. The acetate salt of the compound of claim 1.

23. The trichloroacetate salt of the compound of claim 1.

24. The quaternary ammonium salt of the compound of claim 1.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 1 5,8905% NVENTOWFO I CECIL L. FRYE and JEROME M. KLOSOWSKI It is certified that error appears in the ab0ve-identitied patent and that said Letters Patent are hereby corrected as shown below:

, Page 1 of 2 In the ABSTRACT, the formula should read -NCH Column 9, lines 15-27 the formula should read CH2 I CH2 Column 9, lines t7-5O, the second formula of the claim, should read -o(cs )f B- r r r Page'2 UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT 5, 9 J5 Page 2 of 2 DATED June 17, 1975 INVENTOR( I CECIL L. FRYE and JEROME M. KLOSOWSKI It is certified that error appears in the ab0ve-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 9, lines 5556 the formula -crr 1\1R" should read -CH 9- NR' Y I I2 Column 10, lines 27-29, the formula should read Column 10, line 56 the formula "-CH2-3NR' should read (-CH +s '2 Column 10, line 58 the formula "CI-I2-3NCH3(C6H5) should read -CH23NCH3 6 5) Signed and Sealed this tenth Day of February 1976 [SEAL] Attest:

RUTH C. MASON Arresting Officer C. MARSHALL DANN Commissioner ofPatenrs and Trademarks 

1. A TETRASILA-ADAMANTANE OF THE FORMULA
 2. A compound in accordance with claim 1 wherein at least one R1 substituent is a methyl radical.
 3. A compound in accordance with claim 2 wherein all of the R1 substituents are methyl radicals.
 4. A compound in accordance with claim 1 wherein the R substituent is a -O-Q''-N(R'''')2 radical.
 5. A compound in accordance with claim 4 wherein at least one R1 substituent is a methyl radical.
 6. A compound in accordance with claim 5 wherein all of the R1 substituents are methyl radicals.
 7. A compound in accordance with claim 5 wherein Q'' is an alkylene radical.
 8. A compound in accordance with claim 7 wherein R'' is a methyl radical.
 9. A compound in accordance with claim 8 wherein R is -O(CH2)2N(CH3)2.
 10. A compound in accordance with claim 7 wherein at least one R'''' radical is a hydroxyl-substituted alkyl radical.
 11. A compound in accordance with claim 1 wherein R is a
 12. A compound in accordance with claim 1 wherein R is a -CH2-3NR''''''''2 radical.
 13. A compound in accordance with claim 12 wherein R is a -CH2-3NCH3(C6H5) radical.
 14. A compound in accordance with claim 13 wherein all of the R1 substituents are methyl radicals.
 15. A compound in accordance with claim 1 wherein R is a -ONR''''''''2 radical.
 16. The amine hydrochloride salt of the compound of claim
 1. 17. The sulfate salt of the compound of claim
 1. 18. The amine hydroiodide salt of the compound of claim
 1. 19. The amine hydrobromide salt of the compound of claim
 1. 20. The sulfonate salt of the compound of claim
 1. 21. The phosphate salt of the compouNd of claim
 1. 22. The acetate salt of the compound of claim
 1. 23. The trichloroacetate salt of the compound of claim
 1. 24. The quaternary ammonium salt of the compound of claim
 1. 